add: 单元测试项目

LeetCodeSharp.Tests/LeetCodeSharp.Tests.csproj

@@ -0,0 +1,27 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+
+    <IsPackable>false</IsPackable>
+    <IsTestProject>true</IsTestProject>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="coverlet.collector" Version="6.0.0" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.0" />
+    <PackageReference Include="xunit" Version="2.5.3" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="2.5.3" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\LeetCodeSharp\LeetCodeSharp.csproj" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <Using Include="Xunit" />
+  </ItemGroup>
+
+</Project>

LeetCodeSharp.Tests/P589Tests.cs

@@ -0,0 +1,22 @@
+using LeetCodeSharp.Problems;
+using LeetCodeSharp.Utils;
+
+namespace LeetCodeSharp.Tests;
+
+public class P589Tests
+{
+    [Fact]
+    public void Test1()
+    {
+        Node root = new Node(1, [
+            new Node(3),
+            new Node(2),
+            new Node(4),
+            ]);
+
+        IList<int> except = [1, 3, 2, 4];
+
+        var solution = new Solution();
+        Assert.Equal(except, solution.Preorder(root));
+    }
+}